Remastering 78s & Removing bangs caused by cracks -Sound Forge - PC

Subject:Remastering 78s & Removing bangs caused by cracks Posted by: JAZ Date:1/4/2001 12:34:00 PM I am interested in remastering & preserving the family collection of old SHELLAC 78's. Vinyl records are not a problem, since they never crack. The problem has been that neither SF4.5H nor Noise Reduction 2.0a, have any effect in finding & handling the huge , upto 10 millisec wide clicks caused by a crack in the record (large enough to insert a business card into). At 78 RPM and a 3 minute long record, this could mean 234 painfull manual search & cuts. Even if SF/NR could handle the large click, it would ONLY reduce it in amplitude, leaving a decreased average section still there - which would be incorrect, since the gap is not really "music", just an artifact, caused by the phono-needle crashing into the far edge, which should really be cut out entirely. The sound of the needle in air across the gap, is definitely not a section of music. SOUND FORGE tech support maintains that there is no solution to the problem, other than back breaking, eye straining labour. WRONG! SF4.5 has just the correct solution to this common problem, but requires SF developers to spend a few minutes to fix their software - maybe only about 5 lines of code. The solution is to use the SF4.5 "EFFECTS - GAPPER / SNIPPER" menu item. All you have to do is set the FREQ parameter precisely enough to CUT sections of upto even 1.0 seconds wide, starting at the first huge bang (crack), and repeating for the entire selected section ( which could even be the whole record). SOUND FORGE doesn't realize that this amusing "special effect" is actually a marvelous editing TOOL. You don't actually have to SNIP sections right to the end of the record, since the physical crack in the shellac 78 record gradually narrows and is fairly quiet past halfway through the recording. PROBLEM: This works "almost perfectly", except that SF only allows "ONE SINGLE DECIMAL positon for FREQ" value, which then causes the snip-point to drift further apart after about 8 or 10 seconds of play. You really need more decimals for the FREQ value - 5 would be nice. This is a minor fix that their staff could & should impliment in the next (rev i) update. The other problem you will notice is that the FREQ will not be exactly 1/(78 x 60 ) HZ, for 2 reasons. First, no two turntables (old or new) rotate at precisely 78 RPM, due to motor speeds, friction, and weight of the record & turntable platter. Second, most cracks I have noticed are fairly uniform - in fact radial. The cracks in shellac records seem to start at the edge, and generally extend right to the centre (hub), probably due to the physics of a circular material with a hole at the geometric centric & distribution of mass. However, I have seen some short cracks, even jags that reverse their direction, away from perfectly radial, probably due to differences in density of the shellac as the crack develops. NO PROBLEM. Just high-light the section you need fixed, one at a time if there is a jag, and "adjust" the value of FREQ until the snip positions are correct. This should be a very minor change in decimal position, away from the perfect 78 rpm setting. Mathematically, for those that use a protractor, the change in FREQ for an angular crack, would be = FREQ [+ or -] 1/(1 - sin[crack angle]). The +/- sign depends on whether the crack extends toward the tone arm needle, or away from it. I have experimented with using EFFECTS GAPPER / SNIPPER with a badly crack shellac record, and the results were promising. Just waiting for SOUND FORGE developers to react. So far, just a polite form letter email on my solution, but there is always hope, if there are more customers using their product for 78 restoration. Good luck all. Please let me know what you think, and if you have other solutions to the CRACKED 78 PROBLEM.

I am interested in remastering & preserving the family
collection of old SHELLAC 78's. Vinyl records are not a
problem, since they never crack.
The problem has been that neither SF4.5H nor Noise
Reduction 2.0a, have any effect in finding & handling the
huge , upto 10 millisec wide clicks caused by a crack in
the record (large enough to insert a business card into).
At 78 RPM and a 3 minute long record, this could mean 234
painfull manual search & cuts. Even if SF/NR could handle
the large click, it would ONLY reduce it in amplitude,
leaving a decreased average section still there - which
would be incorrect, since the gap is not really "music",
just an artifact, caused by the phono-needle crashing into
the far edge, which should really be cut out entirely. The
sound of the needle in air across the gap, is definitely
not a section of music.
SOUND FORGE tech support maintains that there is no
solution to the problem, other than back breaking, eye
straining labour.
WRONG! SF4.5 has just the correct solution to this
common problem, but requires SF developers to spend a few
minutes to fix their software - maybe only about 5 lines of
code.
The solution is to use the SF4.5 "EFFECTS - GAPPER /
SNIPPER" menu item. All you have to do is set the FREQ
parameter precisely enough to CUT sections of upto even
1.0 seconds wide, starting at the first huge bang (crack),
and repeating for the entire selected section ( which could
even be the whole record).
SOUND FORGE doesn't realize that this amusing "special
effect" is actually a marvelous editing TOOL.
You don't actually have to SNIP sections right to the
end of the record, since the physical crack in the shellac
78 record gradually narrows and is fairly quiet past
halfway through the recording.
PROBLEM: This works "almost perfectly", except that SF
only allows "ONE SINGLE DECIMAL positon for FREQ" value,
which then causes the snip-point to drift further apart
after about 8 or 10 seconds of play. You really need more
decimals for the FREQ value - 5 would be nice. This is a
minor fix that their staff could & should impliment in the
next (rev i) update.
The other problem you will notice is that the FREQ will
not be exactly 1/(78 x 60 ) HZ, for 2 reasons. First, no
two turntables (old or new) rotate at precisely 78 RPM, due
to motor speeds, friction, and weight of the record &
turntable platter. Second, most cracks I have noticed are
fairly uniform - in fact radial. The cracks in shellac
records seem to start at the edge, and generally extend
right to the centre (hub), probably due to the physics of a
circular material with a hole at the geometric centric &
distribution of mass. However, I have seen some short
cracks, even jags that reverse their direction, away from
perfectly radial, probably due to differences in density of
the shellac as the crack develops.
NO PROBLEM. Just high-light the section you need fixed,
one at a time if there is a jag, and "adjust" the value of
FREQ until the snip positions are correct. This should be a
very minor change in decimal position, away from the
perfect 78 rpm setting. Mathematically, for those that use
a protractor, the change in FREQ for an angular crack,
would be
= FREQ [+ or -] 1/(1 - sin[crack angle]).
The +/- sign depends on whether the crack extends toward
the tone arm needle, or away from it.
I have experimented with using EFFECTS GAPPER / SNIPPER
with a badly crack shellac record, and the results were
promising. Just waiting for SOUND FORGE developers to react.
So far, just a polite form letter email on my solution, but
there is always hope, if there are more customers using
their product for 78 restoration.
Good luck all. Please let me know what you think, and if
you have other solutions to the CRACKED 78 PROBLEM.